Engine starter drive



Y Sept '3, 1946 M. P. WHITNEY ET AL 2,407,048

' ENGINE STARTER DRIVE Filed OCT.. 27, 1944 INVENTOR.

Sept. 3, 1946.

M. P. WHITNEY ET'AL ENGINE STARTER DRIVE Filed Oct. 27, 1944 2Sheets-Sheet 2 I IN V EN TOR. mawiwhwy BY Jani/'e5 Patented Sept. 3,1946 ENGINE STARTER DRIVE.

Maurice P. Whitney, James E. Buxton, and Donald L. Miller, ChemungCounty, N. Y., assignors to Bendix Aviation Corporation,V South Bend,Ind., a corporation of' Delaware Application October 27, 1944, SerialNo. 560,604.

' (ci. '14e-7) The present invention relates to a heavy duty enginestarter drive and more particularly to yielding drive gearing withimproved means for controlling the torque capacity of the gearing andfor insuring proper meshing and demeshing action thereof.

In heavy duty starters such as are used in large armored vehicles 1 andDiesel-powered boats, special problems arise in connection with meshingand demeshing of the gearing due to the high accelerations and stressesinvolved, particularly in view of the controlling weight and spacelimitations. Moreover when a friction clutch is incorporated inthe driveto cushion shockloads, the adjustment and stabilizationof the clutchalso present some diiculties.

It is an object of the present invention to provide a novel heavy dutyengine starter strongly and compactly constructed and which is emcientand reliable inl operation. y

.1t is another object to provide such a device which incorporates novelmeans for. insuring proper meshing action of the gearing.v c

It is another object to providevsuch a device in which a friction clutchis used to limit torque loads and novel means are provided for readilyad- `l'usting and fixing ,the torque capacity of the clutch. y

Further objects and advantages will be apparent from the followingdescription' taken in` conne tion with the. accompanying drawings inwhich:`

Fig. 1 is a side elevation'partly in section of a preferred embodimentof the invention showing the parts of the drive in normal or idleposition.

Fig. 2 is a similar view showing the parts in the position assumed incase of tooth abutmentbetween the drive pinion and the engine gear.

Fig. 3 is a detail in perspective of the. splinedl drive sleeve with thebearing bushing and lock washer shown in disassembled relation thereto.

Fig. 4 is a detail in perspective of certain of the parts of thefriction clutch and its control# ling means shown in disassembledrelation..A l

Fig. 5 is a detail in. perspective oi the'splined barrel and couplingmember disassembled and partly broken away;

Fig. 6 is a perspective detail ofthe drive pinion; and

Fig. 7 is a detail in perspective of the Vstop nut for the drive pinion.

In Fig. l of the drawings there is illustrated a drive shaft I which maybe the extendedarmature shaft of a starter motor not illustrated.` Theend of the shaft is provided with splines as inclicated at 2 and acorrespondingly formed driving sleeve 3 is non-rotatably mounted thereonand projects beyond the end of the shaft. "The projecting portion 4 ofthe sleeve is counterbored to receive a bearing bushing 5 which 'ispressed therein.

Ae Claims.

y vided with external splinesl, and a plurality of friction` clutchplates lilA and 2i) splined alter- A screw shaft V(i is provided with asmooth bearing portion l at one end which fits telescopically A pinionIl] is threaded on thescrew shaft for longitudinal movement into and outof engagement with a gear Il of the engine to be started, the idleposition o-f the pinion being defined by a back-stop I2, and the meshingposition being defined by a stop nut I3 fixed as indicated at I4 to thescrew shaft. An anti-drift spring l5 is preferablyl provided fornormally maintaining the pinion in idle position against the backstop|72.

A barrel member I6 having internal splines l1 is arranged to surroundthe adjacent ends or" the sleeve Il and screw shaft 6. The sleeve 4 ispronately to the sleeved and the barrel l5 are arrangedto bepressed'into frictional contact to form a driving connection from thesleeve to the barrel. jfli'orwthis purpose a thrust ring 2l is seatedadjacent the end of the sleeve against abutment shoulders 22 "(Fig. 3)formed thereon,

and a pressure ring 23 is loosely mounted in the endof the barrel II,jinposition torcompress the clutch discs against vthe thrust ring 2|.Yielding means for actuating the pressure ring 23 are provided in theform o-f an annular series of compression springs 24 which bear at oneend against the pressureyring and at the other end on an abutment ring25 slidably mounted on sleeve 3 and.po sitioned'b,f a nut "2BA threadedon the end of .the sleeve. The nut 42S is locked in adjusted position bymeans of a jam nut 21 also threaded on the `end of the sleeve 3, with adeformable lock washer 23. interposed between the two nuts and,nonrotatably connected to the sleeve as byv means of flattened portionsas shown clearly in Fig. 3.v Pins 29, fixed to the pressure ring 23extend within the springs 24 and prevent radial or tippinglmovementthereof.

A coupling member 30 is rigidly keyedon the end of the screw shaft 6 asindicatedat 3i, being retained thereon by `a lock ring 32. `The couplingmember 30 is provided externally with iiutes springs 35 seated at oneend in openings 33, in the coupling member and at the other endsembracing a series of pins 31 fixed to a backing ring 38 which is alsosplined within the barrel IS. The ring 38 bears against the thrust ring2I for the clutch plates I9, 29; and the latter are retained in thebarrel by a lock ring 3Q whereby the springs 35 are maintained underinitial compression. The fact that the coupling member 3i! and the ring38 are both splined in the interio-r of the barrel I5, effectivelyprevents the springs 35 which are anchored at either end to said membersrespectively, from tipping over or becoming distorted.

The abutting ends of the pinion I and stopnut I3 are preferably formedwith inclined abutments di! and 4I respectively, the engaging surfaces42, 43 of which are at suiciently high angles to the axis of the driveas illustrated to prevent the pinion from sticking in mesh. 'Ihisstructure is more completely illustrated and described in theapplication of Christian, Serial Number 52W ,851, filed March 23, 1944.

In operation, starting with the parts in the positions illustrated inFig. 1, rotation of the J power shaft I by the starting motor istransmitgages the stop-nut I3. The torque 0f the starti ing motor isthen applied to crank the engine, the shock of initial engagementbeingcushioned by the slipping of the clutch discs I9, 23. When theengine starts, the acceleration of the engine gear II returns the pinionI0 toy idle positioned against the back stop I2.

If, during the meshing movement of the pinion I, tooth abutment shouldoccur between the teeth of the pinion and the engine gear as shown inFig. '2, the screw shaft 6 is caused to move to the left against thepressure of the meshenforcing springs 35 until the friction in the screwthreads of the pinion and screw shaft builds up sufciently to rotate thepinion so as to index its teeth into proper registry with the toothspaces of the engine gear. When this occurs, the expansion of thesprings 35 snaps the pinion into initial mesh with the engine gear afterwhich meshing and cranking occur in the usual manner.

It will be understood that the clutch pack is adjusted to transmitsufficient torque to perform the cranking operation but to slip andthereby protect the drive from overloads. In

so adjusting the clutch, the drive sleeve 3 is held stationary in asuitable fixture and the screw shaft is rotated by power while the nut26 is tightened until the torque transmitted through the clutch, asmeasured by any suitable metering means, registers the desired number ofpounds-feet. The jam nut; 21 is then tightened up against the lockwasher 28, and the peripheryof the lock washer hammered down on flats.of the two nuts as shown in Figs. 1 and 2 whereupon the adjustment islocked.

Although but one form of the invention has been shown and described indetail, it will be understood that other forms are possible and variouschanges may be made in the design and arrangement of the parts withoutdeparting from the spirit of the invention as defined in the claimsappended hereto.

What is claimed is' l. In an engine starter drive a power shaft, anexternally splined sleeve fixed thereon, a screw shaft slidablyjournalled at one end in the sleeve, a pinion threaded on the screwshaft for longitudinal movement into and out of mesh with a gear of anengine to be started, a stop nut fixed on the screw shaft defining theoperative position 0f the pinion, a coupling member fixed on the screwshaft and means for frictionally connecting the coupling member torotate with the sleeve including a barrel member splined on the couplingmember, a plurality of clutch plates splined alternately to the sleeveand barrel, said sleeve having a fixed abutment at one end, a pair ofnuts adjustably threaded on the opposite end of the sleeve a deformablewasher between the nuts slidably but non-rotatably mounted on thesleeve, and spring means between said nuts and clutch plates forcompressing the clutch plates against said abutment.

2. In an engine starter, a drive shaft, a barrel member, means-including a friction clutch for connectingthe barrel to the shaft, ascrew shaft, a pinion threaded thereon for longitudinal movement intoand out of engagement with a gear of an engine to b e started, acoupling member fixed to the screw shaft and splined to the barrel, abacking ring non-rotatably connected to the barrel and a plurality of,compression springs between the coupling member and backing ring.

3. An engine starter as set forth in claim 2 including further stopmeans in the barrel for holding the coupling member therein, saidsprings being arranged to yield when, in the meshing movement of thelpinion, a tooth of the pinion abuts against a tooth of the engine gear,until the friction in the screw threads builds up suinciently to indexthe pinion into proper registry with the tooth spaces of the engine gearwhereupon they expand to snap the pinion into initial mesh by moving thecoupling member along its splined connection in the barrel intoengagement with the stop means.

4. In an engine starter a drive shaft, a screw shaft, a sleeve fixed tothe drive shaft and having a telescopic connection with one end of thescrew shaft, a bearing yfor the other end of the screw shaft, anabutment on the screw shaft adjacent the bearing, a pinion threaded onthe screw shaft for movement into and out of mesh with a gear of anengine to be started, a yielding driving connection between the sleeveand screw shaft including a barrel member and a coupling member splinedtherein and fixed to the screw shaft, a backing ring non-rotatablymounted in the barrel and a plurality of compression springs between thecoupling member and backing ring.

5. An engine starter as set forth in claim 4 in which the pinion movestoward said bearing when going into mesh with the engine gear, and thescrew shaft is so mounted in the bearing as to be slidable therein inthe opposite direction against the force of said springs.

6. An engine starter as set forth in claim 4 in which the ends of thecompression springs are so connected to the coupling member and thrustplate that said member and plate serve to keep the springs always inparallel relation to the axis of said screw shaft.

MAURICE P. WHITNEY. JAMES E. BUXTON. DONALD L. MILLER.

